An orthogonal frequency division multiplexing (OFDM) system is a most widely applied communications system in recent years, for example, a Long Term Evolution (LTE) system.
Compared with the LTE communications system, a next-generation communications system not only needs to be improved in performance, but also needs to support a new service type through a new air interface design. In addition to a conventional mobile broadband (MBB) service, the next-generation communications system further needs to support machine-to-machine (M2M) communication, man-computer communication (MCC), and other diversified new services such as ultra-reliable and low latency communications (URLLC) and massive machine type communications (MMTC). A new air interface technology includes technologies in a plurality of dimensions such as coding, a waveform, multiple access, and a frame structure. A waveform technology is a key to flexibly supporting a plurality of services, and is very important for a new air interface of a 5G system.
An orthogonal frequency division multiplexing (OFDM) technology based on a cyclic prefix (CP), that is, CP-OFDM, has a good anti-multipath interference capability and has a good compatibility with various MIMO technologies. An existing OFDM system usually uses the CP-OFDM as a specific solution for a multi-carrier waveform. However, in the CP-OFDM system, a rectangular window is fixedly used for windowing processing. This has obvious defects in suppressing indicators such as an adjacent channel leakage ratio (ACLR) and out-of-band (OOB) power leakage, and leads to an undiversified pulse shape. Therefore, the CP-OFDM system cannot flexibly support a plurality of communication scenarios.